The present invention relates to sanitary absorbent articles such as feminine sanitary napkins and incontinence pads, and, more particularly, to sanitary absorbent articles having side-projecting flaps.
Sanitary absorbent articles generally are large-scale commercially-manufactured articles used to absorb and retain a variety of bodily exudates. Such articles are convenient in that they are often economical yet disposable; they include sanitary napkins, infant diapers, adult incontinence pads and the like.
The technology surrounding sanitary absorbent articles, and particularly feminine sanitary napkins, has undergone several advances over the past two decades. One of such advances was the addition of a flap projecting laterally from each longitudinal side of the article when the article is in a flattened state. Such flaps may comprise integral extensions of a material from which the article is formed or, alternatively, may simply comprise additional material added to the article after its formation.
When such articles are in use, the flaps are folded over the edges of the wearer""s undergarment. They thus may more firmly secure the article to the undergarment, stabilize the article within the undergarment, provide an increased absorptive area for bodily exudates, and help prevent the undergarment from becoming soiled in part by protecting the side edges of the wearer""s undergarment. The flap concept has generally met with success in the marketplace, and articles with flaps of various configurations and conformations are available to the consumer.
Conventional wisdom on the part of both designers and consumers has to date dictated that flaps on absorbent articles should be maximized at their line of juncture with the main body of the article in order to provide a greater area of protection against exudate leakage over the side of the article. Hence, a very common flap configuration is an isosceles (i.e. bilaterally symmetrical) trapezoidal-shaped flap having its base adjoined with the longitudinal side of the main body of the article and projecting (and tapering) away therefrom to the top of the trapezoid. The size of the flap may vary from article to article. Other prior art flap shapes may be loosely described as rectangular, square or mushroom-shaped.
The difficulty with absorbent articles of the trapezoidal and other conventional flap configurations is that the absorbent articles are designed and manufactured in a flat state, while in use the article should generally adopt a two- and often three-dimensional curvature in order to correctly interface with the body of the wearer. By two-dimensional curvature it is meant that the article will curve along one axis of the three-dimensional coordinate system formed by the longitudinal centre-line of the article, the transverse centre-line of the article, and the line perpendicular to both. By three-dimensional curvature it is meant that the article will curve along more than one axis of a three-dimensional co-ordinate system (such a system having three orthogonal axes).
As an example, where the absorbent article is a feminine sanitary napkin, and is in use, a cross-section of the article in both the sagital plane of the wearer""s body (i.e. the longitudinal axis of the article) and the frontal or coronal plane of the wearer""s body (i.e. the transverse axis of the article) would most likely be curved. The flaps, however, are generally designed to be folded about a linear folding axis commonly located along the line of juncture of the flap with the longitudinal side of the main body of the article. The difficulty with such a linear folding axis is that the edges of the wearer""s undergarment, about which the flaps are folded, is curved. Moreover, the undergarment edges usually contain an elastic material for snugly securing the undergarment about the legs of the wearer. Depending on the force exerted by the elastic material, a curved shape may be imparted to the flaps and the central portion of the main body of the article causing them lift off the undergarment and wrinkle, or a flattened shape may be imparted to the edges of the undergarment causing them to not fit snugly against the legs of the wearer. In both cases, the comfort and efficiency of the article and its flaps are sacrificed. Moreover, the larger the flap, the more acute the problem. Thus while large flaps alleviate some difficulties on one hand (i.e. side leakage protection), they create problems on the other (i.e. instability and stress).
To date, most have thought that the benefits afforded by large flaps have outweighed their detriments, so they have been preferred. This has led to substantial efforts to attempt to overcome the difficulties associated therewith. As a result, many different solutions have been attempted in the past to resolve the problems of instability and stress present in absorbent articles of conventional flap design. None to date, however, has been completely satisfactory in that they have always yielded structures that are complex, expensive and/or complicated to manufacture. Moreover, they are often not comfortable for the wearer, or at least could be more comfortable.
An absorbent article having an improved flap configuration that would avoid, alleviate or relieve the stress created in conventional flap configurations as described above, yet while being relatively simple and inexpensive to manufacture is therefore desirable.
It is thus an object of an aspect of the present invention to provide a sanitary absorbent article having an improved flap configuration.
It is a further object of an aspect of the present invention to provide a sanitary absorbent article having a flap configuration having relatively large flaps while having a reduced stress as compared with some of the prior art designs and all-the-while being relatively simple and/or inexpensive to manufacture.
It has been discovered by the present inventors, that, contrary to conventional wisdom, a flap having a configuration generally inverted from those of the prior art is indeed desirable. By inverted it is meant that the flap will generally constantly increase in width (i.e. being substantially constantly divergent) progressing from its proximal side to its distal side (i.e. it is inversely tapered). An example would be a generally isosceles trapezoidal-shaped being larger at its distal side that at its proximal side, i.e. the base of trapezoid being at the distal side of the flap. Such flaps provide the appearance of being relatively xe2x80x9clargexe2x80x9d, yet have reduced stress and increased stability over the prior art flap designs; surprisingly without significantly affecting side leakage protection.
Thus, as embodied and broadly described herein, the present invention provides a sanitary absorbent article comprising:
(A) a main body, said main body having a first longitudinal side, a second longitudinal side generally opposing the first longitudinal side, two generally-opposing transverse sides, and a longitudinal centerline; and
(B) a first flap united with said main body, said first flap projecting laterally from the first longitudinal side of said main body when the article is in a flattened state and being capable of being folded over a crotch portion of a wearer""s undergarment, said first flap having:
(i) a distal side;
(ii) a proximal side generally opposing the distal side of said first flap, the proximal side being adjacent the first longitudinal side of said main body;
(iii) a first transverse side;
(iv) a second transverse side generally opposing the first transverse side of said first flap; and
(v) a garment-facing surface including a fastener for securing said first flap to the garment;
the first transverse side of said first flap and the second transverse side of said first flap being substantially continually divergent from the proximal side of said first flap until an imaginary line parallel to the longitudinal centerline of said main body at approximately a midpoint of said first flap.
Preferably, the sanitary absorbent article further comprises:
(C) a second flap united with said main body, said second flap projecting laterally from the second longitudinal side of said main body when the article is in a flattened state and being capable of being folded about the crotch portion of the undergarment, said second flap having:
(i) a distal side;
(ii) a proximal side generally opposing the distal side of said second flap, the proximal side being adjacent the second longitudinal side of said main body;
(iii) a first transverse side;
(iv) a second transverse side generally opposing the first transverse side of said second flap; and
(v) a garment-facing surface including a fastener for securing said second flap to the undergarment;
the first transverse side of said second flap and the second transverse side of said second flap being substantially continually divergent from the proximal side of said second flap until an imaginary line parallel to the longitudinal centerline of said main body at approximately a midpoint of said second flap.
Advantageously,
(A) the first transverse side of said first flap and the second transverse side of said first flap are substantially straight from the proximal side of said first flap until the imaginary line thereof; and
(B) the first transverse side of said second flap and the second transverse side of said second flap are substantially straight from the proximal side of said second flap until the imaginary line thereof
Of further advantage,
(A) the first transverse side of said first flap and the second transverse side of said first flap are substantially continually divergent from the proximal side of said first flap until the distal side of said first flap; and
(B) the first transverse side of said second flap and the second transverse side of said second flap are substantially continually divergent from the proximal side of said second flap until the distal side of said second flap.
Of still further advantage,
(A) the first transverse side of said first flap and the second transverse side of said first flap are substantially straight from the proximal side of said first flap until the distal side of the first flap; and
(B) the first transverse side of said second flap and the second transverse side of said second flap are substantially straight from the proximal side of said second flap until the distal side of said second flap.
It is preferred that the main body of the article be generally hourglass in shape with rounded ends. When the article is of such a conformation, the first and second transverse sides are the shorter opposing sides and will generally be arcuate. The first and second longitudinal sides are the longer opposing sides and will generally be biconcavely curved. It should be understood however that the shape of such sides is not essential to the invention, and thus the transverse or the longitudinal sides could be either arcuate or straight. Nor is it essential that the main body be generally hourglass-shaped, as articles having main bodies in the shape of a square, rectangle, parallelogram or any other polygon, or even that of an oval or dog-bone, are all within the scope of the present invention. Where such is the case (i.e. where the main body is not rectangular), the longitudinal sides of the layer will be considered to be those opposing sides of a greater relative length as compared with the other opposing sides of the main body. Where it is impossible to make such a determination, any opposing pair of sides may be considered to be the longitudinal sides, or at the limit, opposing portions of any two sides may be considered to be the longitudinal sides. In either case, the transverse sides are the pair of opposing sides (or portions of sides) that are intersected by the longitudinal centre-line of the article, as that line is defined below.
For most articles, the longitudinal centre-line thereof is an imaginary line that extends along the longitudinal axis of the article and bisects the article into two identical or somewhat identical, yet not necessarily mirror image, halves. Similarly, the transverse centre-line is an imaginary line which is perpendicular to the longitudinal center-line and which ordinarily lies along the transverse axis of the article and bisects the article into two identical or somewhat identical, yet not necessarily mirror image, halves.
It is preferred that the flaps be of a generally trapezoidal shape, and still more preferred that the flaps be of the shape of an isosceles (i.e. bilaterally symmetrical) trapezoid. For present purposes, when the flap is of such a shape, it should be considered that the xe2x80x9ctopxe2x80x9d of the trapezoid is the shorter of the two generally parallel sides, and that the xe2x80x9cbasexe2x80x9d of the trapezoid is the longer of the two generally parallel sides. It should be understood that the term xe2x80x9cgenerally parallelxe2x80x9d is meant to encompass sides of a number of different conformations, including those which are slightly curved or angled and those which are formed from two or more straight edges joined at relatively wide angles.
It should expressly be understood, however, that such trapezoidal shape is not essential to the invention. Flaps in the shape of a variety of polygons are all within the scope of the present invention, and will yield similar benefits.
Flaps of the present invention may comprise an integral extension of the materials (or some of the materials) of which the main body of the article is formed. As an example, the flaps may comprise extensions of the cover layer material and the barrier layer material which are joined together, typically about the periphery of the flap. They may also comprise flaps constructed from panels which themselves comprise integral extensions of the materials of which the main body of the article is formed, having been re-affixed to the underside of the main body (i.e. on the garment facing-surface); all as described in commonly assigned co-pending International Patent Application PCT/CA97/00990, filed Dec. 22, 1997, herein incorporated by reference in its entirety. Alternatively, the flaps may comprise additional material added to the main body of the article after the main body""s formation, typically secured to the garment-facing surface of the main body.
In any case, when the article is in a flattened shape (e.g when it is laid on a flat surface), the flaps project laterally from the longitudinal sides of the main body of the article outward (i.e. away from the longitudinal centreline of the article). The flaps are flexible and are capable of being folded about the edge of the crotch portion of a wearer""s undergarment. A distal side of the flap is therefore the side of the flap which is generally opposing (and often parallel to) the longitudinal centreline of the main body and is the side of the flap that is furthest from the point of attachment of the flap to the main body, The distal side of the flap forms the base of the trapezoid (when the flap is trapezoidal shaped.). It is preferably straight or slightly arcuate, i.e. is substantially straight. It should be understood, however, that the distal side of the flap need not comprise a single line or curve. The distal side may thus comprise a series of two or more line segments and/or arcs joined together a relatively wide angles (i.e. greater than 120xc2x0).
Opposite the distal side (and thus in most circumstances intermediate the distal side and the longitudinal centerline) is the proximal side of the flap. Where the flap comprises an integral extension of the material from which the main body of the article is formed, and is not formed from a panel as described above, the proximal side of the flap will be adjoined with the longitudinal side of the main body. Alternatively, where the flap comprises additional material added to the main body after its formation and secured to the garment-facing surface thereof, or where the flap is formed from a panel as described above, the proximal side of the flap is the portion thereof which is adjacent to the longitudinal side of the main body. It will generally thus be that in such situations, the proximal side of the flap is not actually an edge of the flap. Where the proximal side cannot otherwise be defined, it should be considered to be the folding axis of the flap about the undergarment of a wearer of the article. In any case, the top of the trapezoid forms the proximal side of the flap (when the flap is trapezoidal shaped).
It should be understood that flaps constructed in accordance with the teachings of the present invention can have a proximal length of varying dimensions. A length of 6.2 cm is preferred, however, flaps having lengths of less than and greater than 6.2 cm, e.g. 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15 cm, are all within its scope.
The remaining two sides of the trapezoid form the first transverse side and second transverse side of the flap. They are substantially continually divergent from the proximal side of the flap until at least a line parallel to the longitudinal centreline at approximately the midpoint of the flap. The midpoint of the flap is the point equidistant from a first imaginary line connecting the point of intersection of the first transverse side of the flap with the distal side of the flap with the point of intersection of the second transverse side of the flap with the distal side of the flap, and a second imaginary line connecting the point of intersection of the first transverse side of the flap with the longitudinal side of the main body and the point of intersection of the second transverse side of the flap with the longitudinal side of the main body; and also equidistant from the first transverse side of the flap and the second transverse side of the flap.
Preferably, the first transverse side and the second transverse side are substantially continually divergent from the proximal side of the flap until at least the line along which the xe2x80x9clongitudinal lengthxe2x80x9d of the fastener of the flap (as defined hereinbelow) is measured.
Still more preferably, they are substantially divergent from the proximal side until the distal side. The expression xe2x80x9csubstantially continually divergentxe2x80x9d in the context of the present invention should be understood as indicating a situation where the length of imaginary lines from the first transverse side of a flap to the second transverse side of the flap, parallel to the longitudinal centerline of the article, continually increase in a direction away from the proximal side towards the distal side.
Additionally, the substantially constantly divergent portions of the transverse sides are preferably substantially straight. Thus, the flaps would taper from their distal side to the proximal side, such that the distance between the two transverse sides (as measured along a line parallel to the longitudinal centerline of the article) steadily continually decreases from the distal side to the proximal side.
The article, including both the main body and the flaps, will have two opposing major surfaces. These surfaces may be identified by their position when the article is in use. That surface which faces, and is in contact with, the body of the wearer when the article is in use is termed the body-facing surface. The opposing surface is termed the garment-facing surface as in use it will typically face the garments of the wearer (or the external environment if the article is not covered by a garment).
Both the garment-facing surface of the main body and that of the flaps will typically include fasteners that are used to secure the article to wearer""s garments. Advantageously, each of the fasteners located on the garment-facing surfaces of each flap has a longitudinal length not less than 85% of the length of the proximal side of the flap on which the fastener is located. In this context, the term xe2x80x9clongitudinal lengthxe2x80x9d should be understood as the maximum length of the fastener measured along a line parallel to the longitudinal centerline of the article. (For such purposes, gaps in the continuity of the fastener are ignored). The longitudinal length of the fastener may be colloquially termed its width.
It should be understood, however, that it is not necessary for the length of the fastener to exceed the length of the proximal along every line parallel to the longitudinal centerline of the article, only the xe2x80x9clongitudinal lengthxe2x80x9d along a single such line (at the maximum) will suffice.
Still more advantageously, the fastener has a longitudinal length greater than 85% of the proximal side of the flap on which the fastener is located. In this respect, longitudinal lengths of 85%, 90%, and 95% of the proximal side are respectively more preferred. Still even more advantageously the fastener has a longitudinal length not less than the length on the proximal side of the flap on which the fastener is located. In this respect, longitudinal lengths of 100%, 105%, 110% and 115% are respectively still more preferred.
It has been observed that when fasteners of these longitudinal lengths are employed, the central portion of the article has improved stabilization over prior art articles. By improved stabilization it is meant that the article will shift less with respect to the body when the article is in use by a wearer. It is believed that greater fastener longitudinal lengths contribute the stability of the central region of the article.
Preferably, when the article is in a flattened state,
(a) the transverse sides of said first flap each intersect with the first longitudinal side of said main body to form an angle of less than 90xc2x0 and preferably not less than about 60xc2x0; and
(b) the transverse sides of said second flap each intersect with the second longitudinal side of said main body to form an angle of less than 90xc2x0 and preferably not less than about 60xc2x0.
More preferably, each of these angles is approximately 75xc2x0.
It will be understood that the transverse sides of the flaps need not be substantially straight, but may rather be concavely arcuate. Where such is the case, the angle formed as described above should be understood as being the angle formed between the line tangent to the transverse side in question through the point of intersection of that transverse side with the appropriate longitudinal side, and the appropriate longitudinal side.
It has been surprisingly discovered that when the flaps are as described above, most of the benefits of large flaps are provided, however, some of the drawbacks have been alleviated. In this respect, a reduced amount of stress is present, the article is well stabilized within the undergarment of the wearer, and side-leakage protection has not been significantly sacrificed. Without wishing to be bound to any particular theory, it is believed that the stress which would have been created by flaps of the prior art is alleviated as the length of the flap along its folding-axis about the edge of the undergarment of the wearer is reduced relative to the distal edge. Moreover, the increased width of the flap in the distal area allows for the greater adhesive area to be present, and the shape of the flap allows for the total or near total amount of this adhesive to be effective, both of which better fasten the flap to undergarment, and thus secure the article within the undergarment.
Preferably, the fastener of said first flap and the fastener of said second flap each further comprise:
(1) a central zone having an adhesive strength; and
(2) a terminal zone having an adhesive strength, the adhesive strength of the terminal zone being less than the adhesive strength of the central zone.
In this respect, a fastener may loosely be divided into three zones, a first terminal zone closer to the first transverse side of the flap, a second transverse zone closer to the second transverse side of the flap, and a central zone intermediate the two terminal zones. As used herein, the term xe2x80x9czonexe2x80x9d should be understood as including discontinuities (e.g. gaps) in the fastener which the length of such gaps is small relative to the longitudinal length of the fastener.
Moreover, in the preferred embodiment, the terminal zone of each of the fasteners does include a plurality of discontinuities (e.g. gaps) for reducing the adhesive strength of the terminal zone relative to the central zone. Other methods, however, will also suffice. For example, it would be possible to have the physical chemical properties of the adhesive in the terminal zone differ from that in the central zone (e.g. by having different chemical formulations). It would also be possible to coat the adhesive in the terminal zone with a substance, such as talc, which would partially bind to the adhesive reducing its overall adhesive strength. Finally, it would also be possible simply to apply less adhesive (i.e. of a reduced surface area) in the terminal zone.
Most preferably, the sanitary absorbent article is a feminine sanitary napkin, i.e. it is placed in the pudendal region of a female and is used to absorb menses and other discharged fluids.